This invention relates to the formation of a paper overlaid product, and more particularly relates to the formation of a paper overlaid product which uses solid wood or similar unstable type base portion as the substrate, and to the product formed thereby.
Paper overlaid wood products have heretofore been manufactured for various purposes. Such products are formed by pressing an overlay onto a substrate at elevated temperatures and pressures to cure the resin and form a smooth, hard surface for various purposes, such as to increase weatherability and durability, hardness, paintability, chemical resistance and other purposes. For example, U.S. Pat. No. 4,541,880 is directed to overlaid plywood panels manufactured by affixing one or more sheets of thermosetting resin-impregnated fiber overlay paper to one or both sides of he panels at temperatures of from 250.degree. F. to 300.degree. F. and pressures of from 150 to 250 psi. U.S. Pat. No. 3,666,593 is directed to a paper overlaid panel that uses a particular group of thermosetting resins serving both as the impregnant and the adhesive, such resins being applied at around 300.degree. F. and pressures of 150 psi and up. Some overlays are applied at greatly elevated temperatures and pressures, such as illustrated in U.S. Pat. No. 4,263,373 wherein temperatures range up to 200.degree. C. and pressures up to 2,000 psi.
Although resin impregnated paper overlays can be pressed onto the more stable substrates such as plywood or other pressed products at elevated temperatures and pressures while curing the resin and at the same time achieve a reasonably good surface, as seen in the prior patents, such overlays cannot be satisfactorily similarly pressed onto unstable substrates, for example, solid wood, at elevated temperatures and pressures since imperfections develop in the finished product. That is, when solid wood for instance is subjected to elevated temperatures and pressures for applying a resin treated overlay thereto, pitch can bleed from the substrate through the overlay, thus causing surface contamination, a surface that is unsuitable for painting, and a surface that is not easily cleaned. Also, subjecting solid wood to hot pressing and high pressures causes thickness variation in the final product and also an uneven surface thereon due to varying densities inherent in the substrate. Furthermore, the hot pressing and high pressures required to cure the resins cause surface imperfections in the substrate which can telegraph through the overlay.